Alloy steel particularly adaptable for use as a filler metal

ABSTRACT

An alloy particularly adaptable for use as a welding filler wire contains from 4 percent to 8 percent nickel, about 5 percent to about 11.5 percent chromium, about 1 percent to about 3.75 percent molybdenum, up to about 0.5 percent aluminum, up to about 0.3 percent titanium, up to about 0.03 percent carbon and the balance essentially iron. The alloys are also useful for structural and other applications.

firmed e tates Patent [1 1 Kenyon Oct. 30, 1973 {5-4} ALLQY STEELPARTICULARLY' 2,185,996 1/1940 Hatfield 75/128 W ADAPTABLE FOR USE s AFILLER 3,278,298 10/1966 Perry 75/128 W METAL 3,556,776 1/1971 Clarke75/128 W 3,594,158 7/1971 Sadowski 75/128 W Norman Kenyon, Sloatsburg,N.Y.

The International Nickel Company, Inc., New York, N.Y.

Filed: Apr. 5, 1971 Appl. No.: 131,510

Inventor:

Assignee:

U.S. Cl. 75/128 W, 75/124, 75/128 T Int. Cl. C22c 39/20 Field of Search75/128 W References Cited UNITED STATES PATENTS 9/1936 McIntosh 75/128 WPrimary ExaminerHyland Bizot AttorneyMaurice L. Pinel [57] ABSTRACT 5Claims, No Drawings ALLOY STEEL PARTICULARLY ADAPTABLE FOR USE AS AFILLER METAL 11 percent nickel, 8.75 percent to 11.5 percent chro-'mium, 1.4 percent to 3.75 percent molybdenum, at least one metal fromthe group consisting of aluminum and titanium in a total amount of 0.1percent'to 0.65 percent, the aluminum not exceeding 0.4 percent and thetitanium not exceeding 0.3 percent, carbon up to 0.04 percent, pp to 0.5percent each of silicon and manganese, with the balance beingessentially iron.

However, as is not uncommon with the development of new alloys variousdifficulties oftenarise and the above-described steels proved not to bean exception. For a rather frustrating problem evo'lved-in usingmatching filler metal compositions the steels could be welded over afairly wide range of section sizes, e.g., from sheet to at least 1 inchthick plate, by the gas tung- In carrying the invention into practice,while the upper chromium percentage might be extended up to l 1.5percent it is much preferred that it not exceed l l percent in order toavoid retained austenite. On the sten-arc (TIG) process, but in usingthe much faster,

less expensive conventional gas metal-arc (MIG) procedure, weld crackingmanifested itself in respect of the thicker plate sections, i.e., abovel/2 inch, and a substantial amount of impact toughness was lost evenwith sections on the order of 1/2 inch.

Now, as is well recognized, the weldability of an alloy is of vitalimportance to its commercial success in innumerable and diverse areas ofapplication. This being the case, it became a prime objective-to find asolution to the MIG problem in order to take advantage of the economicsoffered by this technique and to remove an otherwise expected deterrentto the full commercial exploitation of the 10-1'0-2 steels, steels whichhad already demonstrated many attractive qualities. Of course, thisrequired a filler material which would not only provide weld depositsfree of deleterious cracks but which were also characterized'bymechanical properties approximating those of the l0-10-2 base'materialwelded. It would be no solution to achieve crack-free deposits at theexpense of other indispensible metallurgical properties.

It has now been discovered that the above described problem is greatlyminimized if not entirely obviated with novel filler metals containingcorrelated amounts of nickel, chromium, molybdenum, aluminum, titanium,etc., as herein described. Moreover, it has been further found that suchfiller metals are suitable for use in the welding of steels which differcompositionally from the 10-10-2 steels and this lends to theircommercial significance.

Generally speaking, the present invention contemplates filler metalsformed from alloys containing (in weight percent) from about 4 percentto less than 8 percent, e.g., 7.85 percent, nickel, about 8.5 percent to11 percent chromium, about 1 percent to about 3.5 percent or 3.75percent molybdenum, up' to about 0.5 percent aluminum, up to about 0.3percent titanium, up to about 0.03 percent carbon, and the balanceessentially iron.

other hand, while the chromium level might be extended down to as low as5 percent or 6 percent where the intended use will not suffer for wantof corrosion resistance, where the latter is of importance the tillermetal should contain at least 8 percent chromium.

The nickel content should be less than 8 percent to again minimizeretained austenite. Furthermore, it has been determined that deposits ofexcellent toughness are obtained despite what might otherwise beconsidered as a low nickel plateau. This obtains down to as low as 6percent nickel without significant loss in strength or corrosionresistance being encountered. At nickel levels of 4 percent, strength islowered but such filler metals are deemed useful in welding alloys otherthan those of 10-10-2 type.

With regard to the constituents molybdenum, aluminum and titanium, theseelements do not seemingly play a role significantly different from theirrespective roles in the l0-l0-2 steel. Molybdenum contributes tocorrosion resistance and strength and the aluminum and titanium conferage hardening and strength.

A most advantageous filler metal in accordance herewith consistsessentially of from about 6 percent to 7.8 percent nickel, about 9percent to 10.5 percent chr0- mium, about 1.25 percent to 2.75 percentor 3 percent molybdenum, about 0.05 percent to 0.4 percent aluminumand/or about 0.05 percent to about 0.3 percent titanium, up to 0.03percent carbon and the balance essentially iron. Another most preferredcomposition contains about 6 percent to 7.5 percent nickel, about 9.5percent to 10.5 percent chromium, about 1.5 percent to about 2 percentmolybdenum, about 0.1 percent or 0.2 percent to 0.4 percent aluminum,about 0.1 percent or 0.2 percent to'0.3 percent titanium, up to about0.1 percent each of silicon and manganese, up to about 0.03 percentcarbon and the balance essentially iron.

' For the purpose of giving those skilled in the art a betterappreciation of the invention the following illustrative data are given.

Several 30-pound heats were vacuum melted, cast, worked and drawn downinto filler metal welding wires 0.062 inch in diameter, the fillermetals having compositions as given in Table I. Included in Table I isthe composition of the 10-10-2 base plate (B.P.) welded. Filler metal Ais without the invention whereas the others are within thescope'thereof.

Each of the wires was used to form a gas metal-arc weld (MIG) betweentwo 1 inch thick sections of the base plate. The base plate had beenaged for 3 hours at 900 F. and was in the restrained condition, i.e.,heavy U-straps were used to restrain the welded joint to a 2- inch thicksteel platen. The joint design was a single U- groove with a 15 sideangle, a 1/4 inch root radius, and a 3/32 inch root face. The jointswere filled in 10 passes, the welds being made at 30 volts, 300 amperes,and a 12 inch per minute travel speed while feeding 200 inches perminute of filler wire. Argon, flowing at about 50 cubic feet per hour,was used as the shielding gas and no preheat was utilized. The interpasstemperature was maintained at or below about 200 F.

TABLEv 1 Percent Filler Ni Cr Mo Al Ti C Mn Si Fe A 9.8 9.3 1.95 .25 .16.003 .14 .09 Bal. 1 7.8 9.5 1.99 21 .19 .004 .14 .07 Hal. 2 5.9 9.5 1.9817 .17 .002 .13 .08 B211. 3 6.1. 9.5 1.91 .28 .18 .001 .081 .11 Bal. 44.3 8.9 1.95 .16 .24 .011 .075 .096 Bal. 13.1. 10.0 10.5 2.1 .40 .23.032 .1 1 .09 3211.

The weld deposits were radiographically examined, Charpy V-notch samplesmachined from the bars and polished and etched transverse slices takenfrom yielded the following results: the deposits were microscopicallyexamined at 30x TABLE I magnification. Standard transverse tensile andCharpy 15 V-notch specimens were machined from the welds and CVN oFiller Y.S. U.T.S. El. R.A. RT then aged at 900 F. for 3 hours beforetest. These re l 163g [To 715 140 M4 sults (average) are reported inTable 11. 2 141.6 147.5 19.0 74.0 175,150

TABLE 11 El. R.A. Weld Microscopic Y.S. U.T.S. (per- (per- CVN depositX-ray at30x (1 .s.i.) (k.s.i.) cent) cent) (ft. lbs.)

A sound cracks 166.4 170.1 8 33 22 1 ...do..... nocracks 173.7 175.3 1360.5 48 2 160.5 161 14 67 87 3 161.4 163 13 60.5 77 4 129.1 135.7 1572.5 150 It will be observed from the foregoing data that although eachof the five weld deposits was seemingly 30 crack-free upon radiographicexamination, cracks were detected during microscopic examination of thedeposit formed using Filler Metal A. Despite the fact that Filler Metalsl and 2 were of considerably lower nickel content than the matchingFiller Metal A, no appreciable loss in toughness or strength wasexperienced; in fact, an increase of toughness was obtained.

It should be pointed out, that the strength level of the depositobtained using Filler Metal 4 was relatively low; however, the toughnessof this deposit was extremely high. These data indicate that such fillermetals are useful in welding other materials. In this connection it isconsidered that steels, particularly cast steels, of the followingcomposition would be amenable to welding with such welding wires:percent to l 1 percent nickel, percent to percent chromium, the sum ofthe nickel plus chromium being from 18 percent to 22 percent, about 0.5percent to 3 percent silicon, titanium and/or aluminum up to 0.2 percenteach, up to 1 percent manganese, up to 0.5 percent carbon and thebalance essentially iron.

While the subject invention as above described has been set forth solelyin connection with filler welding wires, the alloy compositionscontemplated herein are also suitable for use in sundry other areaswhere steels capable of affording a good combination of strength,toughness, corrosion-resistance, workability, fabricability, etc., wouldfind utility. Specifically, such compositions are considered useful inthe production of steel castings for such potential applications aspumps and impellers and as structural members for applicationsparticularly requiring corrosion resistance and high toughness. Asillustrative of the latter utility, the Fillers l and 2 of Table l werealso produced as l/2 inch hot rolled bars which were then annealed atl,500 F. for 1 hour and aged at 900 F. for 3 hours. Tensile and Pressurevessels and sheet for architectural purposes are also contemplated foruse in accordance herewith.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to without departing from the spirit andscope of the invention, as those skilled in the art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the invention and appended claims.

1 claim:

1. An alloy adaptable for use as a welding filler material andconsisting essentially of from 4 percent to 7.85 nickel, about 8.5percent to about 11 percent chromium, about 1 percent to about 3.75percent molybdenum, up to about 0.5 percent aluminum, up to about 0.3percent titanium, up to about 0.03 percent carbon and the balanceessentially iron.

2. An alloy in accordance with claim 1 containing at least 6 percentnickel, at least 8 percent chromium, about 1.25 percent to 2.75 percentmolybdenum, about 0.05 percent to 0.4 percent aluminum and/or about 0.05percent to 0.3 percent titanium.

3. An alloy in accordance with claim 1 in which the aluminum is from 0.2percent to 0.4 percent and the titanium is from 0.2 percent to 0.3percent.

4. A filler metal welding wire formed from the alloy set forth in claim1.

5. A filler metal welding wire formed from the alloy set forth in claim2.

2. An alloy in accordance with claim 1 containing at least 6 percent nickel, at least 8 percent chromium, about 1.25 percent to 2.75 percent molybdenum, about 0.05 percent to 0.4 percent aluminum and/or about 0.05 percent to 0.3 percent titanium.
 3. An alloy in accordance with claim 1 in which the aluminum is from 0.2 percent to 0.4 percent and the titanium is from 0.2 percent to 0.3 percent.
 4. A filler metal welding wire formed from the alloy set forth in claim
 1. 5. A filler metal welding wire formed from the alloy set forth in claim
 2. 